1. Field of the Invention
The present invention relates to a printing apparatus for use in the manufacture of semiconductor integrated circuit elements, such as IC, LSI or ultra-LSI, and more particularly to a printing apparatus for forming an image of a mask on a wafer to print a mask pattern thereon through an optical mirror imaging system.
2. Description of the Prior Art
An optical mirror imaging system is already known for example as disclosed in U.S. Pat. No. 3,748,015 and in the U.S. patent application Ser. No. 701,946. Also a printing apparatus utilizing an optical mirror imaging system is already known as disclosed in the German OLS No. 2410924. In said known apparatus, however, the mask and wafer are subjected to scanning by rotary motion about a point at the printing. For this reason there may result an unevenness in the exposure as the speed varies from a position close to the center of rotation to a position apart therefrom.